The Spectacular Ultraviolet Flash From the Type Ia Supernova 2019yvq. (arXiv:2005.05972v1 [astro-ph.HE])

The Spectacular Ultraviolet Flash From the Type Ia Supernova 2019yvq. (arXiv:2005.05972v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Miller_A/0/1/0/all/0/1">A. A. Miller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Magee_M/0/1/0/all/0/1">M. R. Magee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Polin_A/0/1/0/all/0/1">A. Polin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maguire_K/0/1/0/all/0/1">K. Maguire</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zimmerman_E/0/1/0/all/0/1">E. Zimmerman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yao_Y/0/1/0/all/0/1">Y. Yao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sollerman_J/0/1/0/all/0/1">J. Sollerman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schulze_S/0/1/0/all/0/1">S. Schulze</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Perley_D/0/1/0/all/0/1">D. A. Perley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kromer_M/0/1/0/all/0/1">M. Kromer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bulla_M/0/1/0/all/0/1">M. Bulla</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Andreoni_I/0/1/0/all/0/1">I. Andreoni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bellm_E/0/1/0/all/0/1">E. C. Bellm</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+De_K/0/1/0/all/0/1">K. De</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dekany_R/0/1/0/all/0/1">R. Dekany</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Delacroix_A/0/1/0/all/0/1">A. Delacroix</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dhawan_S/0/1/0/all/0/1">S. Dhawan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fremling_C/0/1/0/all/0/1">C. Fremling</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gal_Yam_A/0/1/0/all/0/1">A. Gal-Yam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goldstein_D/0/1/0/all/0/1">D. A. Goldstein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Golkhou_V/0/1/0/all/0/1">V. Z. Golkhou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goobar_A/0/1/0/all/0/1">A. Goobar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Graham_M/0/1/0/all/0/1">M. J. Graham</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Irani_I/0/1/0/all/0/1">I. Irani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kasliwal_M/0/1/0/all/0/1">M. M. Kasliwal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaye_S/0/1/0/all/0/1">S. Kaye</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_Y/0/1/0/all/0/1">Y.-L. Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Laher_R/0/1/0/all/0/1">R. R. Laher</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mahabal_A/0/1/0/all/0/1">A. A. Mahabal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Masci_F/0/1/0/all/0/1">F. J. Masci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nugent_P/0/1/0/all/0/1">P. E. Nugent</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ofek_E/0/1/0/all/0/1">E. Ofek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Phinney_E/0/1/0/all/0/1">E. S. Phinney</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prentice_S/0/1/0/all/0/1">S. J. Prentice</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Riddle_R/0/1/0/all/0/1">R. Riddle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rigault_M/0/1/0/all/0/1">M. Rigault</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rusholme_B/0/1/0/all/0/1">B. Rusholme</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schweyer_T/0/1/0/all/0/1">T. Schweyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shupe_D/0/1/0/all/0/1">D. L. Shupe</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Soumagnac_M/0/1/0/all/0/1">M. T. Soumagnac</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Walters_R/0/1/0/all/0/1">R. Walters</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yan_L/0/1/0/all/0/1">L. Yan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zolkower_J/0/1/0/all/0/1">J. Zolkower</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kulkarni_S/0/1/0/all/0/1">S. R. Kulkarni</a>

Early observations of Type Ia supernovae (SNe$,$Ia) provide essential clues
for understanding the progenitor system that gave rise to the terminal
thermonuclear explosion. We present exquisite observations of SN$,$2019yvq,
the second observed SN$,$Ia, after iPTF$,$14atg, to display an early flash of
emission in the ultraviolet (UV) and optical. Our analysis finds that
SN$,$2019yvq was unusual, even when ignoring the initial flash, in that it was
moderately underluminous for a SN$,$Ia ($M_g approx -18.5$$,$mag at peak)
yet featured very high absorption velocities ($v approx
15,000$$,mathrm{km,s}^{-1}$ for Si II $lambda$6355 at peak). We find that
many of the observational features of SN$,$2019yvq, aside from the flash, can
be explained if the explosive yield of radioactive $^{56}$Ni is relatively low
(we measure $M_{^{56}mathrm{Ni}} = 0.31 pm 0.05,M_odot$) and it and other
iron-group elements are concentrated in the innermost layers of the ejecta. To
explain both the UV/optical flash and peak properties of SN$,$2019yvq we
consider four different models: interaction between the SN ejecta and a
nondegenerate companion, extended clumps of $^{56}$Ni in the outer ejecta, a
double-detonation explosion, and the violent merger of two white dwarfs. Each
of these models has shortcomings when compared to the observations; it is clear
additional tuning is required to better match SN$,$2019yvq. In closing, we
predict that the nebular spectra of SN$,$2019yvq will feature either H or He
emission, if the ejecta collided with a companion, strong [Ca II] emission, if
it was a double detonation, or narrow [O I] emission, if it was due to a
violent merger.

http://arxiv.org/icons/sfx.gif